Simplify the following expression: $t = \dfrac{3}{10x} - \dfrac{1}{2x}$
Answer: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $10x$ and $2x$ $\lcm(10x, 2x) = 10x$ $ t = \dfrac{1}{1} \cdot \dfrac{3}{10x} - \dfrac{5}{5} \cdot \dfrac{1}{2x} $ $t = \dfrac{3}{10x} - \dfrac{5}{10x}$ $t = \dfrac{3 -5}{10x}$ $t = \dfrac{-2}{10x}$ Simplify the expression by dividing the numerator and denominator by 2: $t = \dfrac{-1}{5x}$